Bay Bridge: Will Bay Area regret or rejoice its choice to build unique self-anchored suspension span?

OAKLAND -- It's been called graceful, sleek and futuristic. A New York Times architecture critic once compared it to a Jungian scholar's symbolic "Ladder to Heaven."

But will the Bay Area's decision to build the world's largest steel, single-tower self-anchored suspension span rather than a plain vanilla viaduct be worth the $6.4 billion and the decade it took to build it?

News of snapped -- and inaptly named, as it turns out -- high-strength steel anchor rods in one of the new Bay Bridge's key seismic junctions, coupled with the possibility of another delay, is stirring up old debates about choosing form over function.

An artist rendering of the final Bay Bridge design.
Courtesy of the Toll Bridge Program Oversight Committee

On Tuesday afternoon, the Senate Transportation Committee -- whose chairman, Mark DeSaulnier, voted for the innovative single-tower design when he was a Contra Costa County supervisor -- will grill Caltrans about whether the agency sacrificed structural soundness for aesthetics.

The broken rods are among tens of thousands of pounds of high-strength steel components designers chose to use in the Bay Area's unique bridge of choice: An all-white, 525-foot pentagonal tower hung with a looping catenary cable that accentuates slim, 2.1-mile side-by-side horizontal decks designed to "leap" off Yerba Buena Island, gently bank and hover over the bay before descending into Oakland.

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"Is this a case of top engineers and designers, given an outsized goal, reaching too far beyond our own understanding?" reads a committee background paper prepared for the Capitol hearing. "Or were the bridge developers, so driven by design, forced to adopt unreliable methods in order to fit a mold only tangible in dreams?"

To attain the architects' vision of a slim and delicate span that almost appears to float on the horizon and fulfill the Bay Area's high expectations, designers had to compact and stuff the guts of many of the bridge's structural supports into constrained spaces.

Balancing mass, weight, cost and architecture during design is "not a unique challenge to the bridge," countered Metropolitan Transportation Commission Executive Director Steve Heminger, one of three members of the Toll Bridge Program Oversight Committee. "Clearly, if the east pier (where the bolts broke) had been larger, there might have been room for more bolts. But I'm still waiting to review all the documents."

The strength of the steel used in the bolts also was an issue, officials conceded last week. The stronger the steel, the less steel is needed to do the job for which it is intended. But the stronger the steel, the more susceptible it is to a well-known embrittlement phenomenon in which hydrogen atoms invade its crystalline molecular structure and weaken its holding power.

Experts blame hydrogen for fracturing three dozen rods on the bridge in March, forcing Caltrans to pursue repairs that could cost $10 million and push out the scheduled Sept. 3 opening.

The bolts are part of the critical large seismic stabilizers -- an 11-foot-wide by almost-6-foot-thick concrete square drilled with vertical holes -- that sit out of sight below the bridge deck and just above the two columns on the pier east of the main span tower.

Don't blame the design, T.Y. Lin International lead engineer Marwan Nader countered after a Bay Area Toll Authority meeting last week.

"The issue is that the (rods) did not perform as they were expected," said Nader, of Walnut Creek.

No one would be fretting over bad metallurgy had the Bay Area acquiesced in February 1997 when then-Gov. Pete Wilson proposed to replace the quake-vulnerable eastern cantilevers between Oakland and Yerba Buena Island with a simpler concrete skyway.

Instead, angry voices railed about the state's "freeway on stilts." East Bay leaders demanded equal architectural stature with San Francisco's western side of the Bay Bridge.

"Icons come about because of people with vision," then-Oakland Mayor Jerry Brown (now governor) told the San Francisco Chronicle at the time. "It's unfortunate the pencil-pushers, bureaucrats and political yahoos don't understand quality and try to block quality to save a few bucks."

Wilson listened. He told the Bay Area it could have all the bridge it wanted as long as it paid for it.

So, local leaders launched a broad, unprecedented and often kooky public input process. In mid-1998, the Metropolitan Transportation Commission selected the single-tower self-anchored suspension span and skyway combination.

Conceived by renowned San Francisco architect Donald MacDonald and designed by T.Y. Lin's Nader and veteran Caltrans bridge engineer Brian Maroney, it is the largest bridge of its kind in the world.

A consulting team the state hired a few years ago to study the span's skyrocketing price tag would also call it one of the "most costly, complex and challenging bridge projects in U.S. history."

"I was asked over and over again, 'Is it buildable?' " Maroney said earlier this year during an interview on the span. "Yes, it is buildable. But that's the wrong question. It should be, 'How do you build it?' "

Engineers had to minimize the mass and mold the appearance of the structural supports to meet architectural demands for an unobstructed "thin white" line, all while meeting stringent seismic safety requirements and traffic loads. The project pushed engineers to their limits, Maroney has said.

The most spectacular example is the way engineers have almost hidden the anchorages for each end of the looping steel cable beneath the travel lanes -- a slight bulge in the deck east of the main tower is the only visible sign, and access is essentially a crawl space.

Anchorages in traditional suspension bridges such as the Golden Gate Bridge are massive, cathedral-sized structures that house the splayed cable ends on opposite shores.

But Maroney has also repeatedly stressed the extensive testing to which the design team has subjected nearly every innovative bridge element before they were installed on the span.

"There's blood on the cutting edge," he said. "That's why they call it the cutting edge. If we didn't have proved, time-tested data, then I wanted to go into the laboratory."

The University of Nevada, Reno's seismic researchers, for example, put steel shear links that tie together the main span tower's four segments into their earthquake simulator. The University of San Diego shook, bent and pounded bridge columns to ensure they would take a big quake.

The broken bolts are fixable, MTC's Heminger said, much like the many engineering challenges the design team and contractors have overcome since construction started in 2002 -- nearly all of them more technically difficult than devising a shear key repair.

The Bay Area won't regret its one-of-a-kind design choice, he predicted.

"Yes, the bolts was a 'D'oh!' moment," Heminger said. "But bridges help define the Bay Area. Bridges tie together the disparate parts of our region. They are on our post cards and on our logos and they serve not only as a source of transportation, they are almost a part of our psychology.

"I believe the opportunity that (Wilson) gave us back in 1997 really resonated with people, and it still does."

FAST FACTS: BAY BRIDGE
Time and money -- When the Bay Area chose the self-anchored suspension span design in 1998, it was supposed to cost $1.1 billion and open in 2003. Since then, the price has soared nearly sixfold to $6.4 billion and the opening date pushed out a decade.
Seismic zone -- Designed to last 150 years, the state classifies the Bay Bridge as a "lifeline span," its highest safety rating, which means it is expected to be in service within 24 hours of an earthquake generating motions that are estimated to occur once every 1,500 years. The bridge is located within 10 miles of the Hayward and San Andreas faults.
Weighty matters -- The self-anchored suspension span weighs 51,800 tons, the equivalent of about 761,000 people with an average weight of 150 pounds apiece.
Source: BANG research, Bay Area Toll Authority, Caltrans